Exam on wed 1/3 Fill in the Blank



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  • Transgenic mice extremely useful in studying diseases
  • EXAM ON WED
  • 1/3 Fill in the Blank
  • 1/5 definitions
  • 1/5 short answer
  • Few true and false
  • 1/3 Essay or Critical Thinking
  • QUESTIONS??
  • pituitary gland is Master Gland
  • anterior pituitary (adenohypophysis)
  • classical gland composed predominantly of cells that secrete protein hormones.
  • posterior pituitary (neurohypophysis) -not really an organ, but an extension of the hypothalamus. composed largely of the axons of hypothalamic neurons which extend downward as a large bundle behind the anterior pituitary. It also forms the so-called pituitary stalk, which appears to suspend the anterior gland from the hypothalamus.
  • Hormones of the Pituitary
  • pituitary gland - pea-sized structure located at the base of the brain.
  • In humans, it consists of two lobes:
  • Anterior Lobe
  • Posterior Lobe
  • The Anterior Lobe
  • The anterior lobe contains 6 types of secretory cells, all but one of which are specialized to secrete only one of the anterior lobe hormones.
  • All of them secrete their hormone in response to hormones reaching them from the hypothalamus of the brain
  • Thyroid Stimulating Hormone (TSH)
  • TSH (also known as thyrotropin) –glycoportein consisting of:
  • a  chain of 112 amino acids and
  • an  chain of 89 amino acids.
  • The  chain is identical to that found in two other pituitary hormones, FSH and LH as well as in the hormone chorionic gonadotropin.
  • The secretion of TSH is
  • -stimulated by the arrival of thyrotropin releasing hormone (TRH) from the hypothalamus.
  • -inhibited by the arrival of somatostatin from the hypothalamus.
  • As name suggests, TSH stimulates the thyroid gland to secrete its hormone thyroxine (T4). It does this by binding to GPCRs on the surface of the cells of the thyroid.
  • .
  • Some people develop antibodies against their own TSH receptors. When these bind the receptors, they "fool" the cell into making more T4 causing hyperthyroidism. The condition is called thyrotoxicosis or Graves' disease.
  • A deficiency of TSH causes hypothyroidism: inadequate levels of T4 (and thus of T3 ).
  • Recombinant human TSH has recently become available to treat patients with TSH deficiency.
  • Some people inherit mutant TSH receptors. This can result in hypothyroidism.
  • A deficiency of TSH, or mutant TSH receptors, have also been implicated as a cause of osteoporosis. Mice, whose TSH receptors have been knocked out, develop increased numbers of bone-reabsorbing osteoclasts.
  • Follicle-Stimulating Hormone (FSH)
  • FSH is a heterodimeric glycoprotien consisting of
  • - same  chain found in TSH (and LH)
  • -  chain of 115 amino acids (gives it its unique properties)
  • Synthesis and release of FSH is triggered by the arrival from the hypothalamus of gonadotropin releasing hormone GnRH
  • Effect of FSH depends on one's sex
  • FSH in females
  • In sexually-mature females, FSH (assisted by LH) acts on the follicle to stimulate it to release estrogens
  • FSH in males
  • In sexually-mature males, FSH acts on spermatogonia (with the aid of testosterone) stimulating the production of sperm.
  • Luteinizing Hormone (LH)
  • LH is synthesized within the same pituitary cells as FSH and under the same stimulus (GnRH).
  • Heterodimeric glycoprotein
  • -same 89 aa  subunit found in FSH & TSH
  • -  chain of 115 aa that is responsible for its properties.
  • Effects of LH also depend on sex
  • LH in females
  • In sexually-mature females, LH
  • stimulates the follicle to secrete estrogen in the first ½ of the menstrual cycle
  • a surge of LH triggers the completion of meiosis I of the egg and its release (ovulation) in the middle of the cycle
  • stimulates the now-empty follicle to develop into the corpus luteum, which secretes progesterone during the latter ½ of the menstrual cycle.
  • LH in males
  • LH acts on the interstitial cells (also known as Leydig cells) of the testes stimulating them to synthesize and secrete the male sex hormone, testosterone.
  • LH in males is also known as interstitial cell stimulating hormone (ICSH).
  • Prolactin (PRL)
  • 198 aa
  • During pregnancy it helps in the preparation of the breasts for future milk production.
  • After birth- promotes the synthesis of milk.
  • Prolactin secretion is
  • stimulated by TRH
  • repressed by estrogens and dopamine
  • In pregnant mice, prolactin stimulates the growth of new neurons in the olfactory center of the of the brain.
  • Growth Hormone (GH)
  • also called somatotropin
  • 191 aa
  • GH-secreting cells are stimulated to synthesize and release GH by the intermittent arrival of growth hormone releasing hormone (GHRH) from the hypothalamus.
  • GH promotes body growth by:
  • binding to receptors on the surface of liver cells
  • this stimulates them to release insulin-like growth factor-1 (IGF-1; also known as somatomedin)
  • IGF-1 acts directly on the ends of the long bones promoting their growth
  • Things that can go wrong
  • In childhood-hyposecretion of GH produces the stunted (but normally well-proportioned) growth of a midget.
  • Growth retardation can also result from an inability to respond to GH. This can result from inheriting mutant genes encoding the receptors for GHRH or GH or a defect in STAT 5B.
  • In adults, a hypersecretion of GH leads to acromegaly.
  • Hormone-replacement therapy
  • GH from domestic mammals like cows and pigs does not work in humans. So for many years, the only source of GH for therapy was that extracted from the glands of human cadavers. This supply was shut off when several patients died from a rare neurological disease attributed to contaminated glands.
  • Now, with recombinant DNA methods, recombinant human GH (rHGH) is available.
  • While a great benefit to patients suffering from GH deficiency, there has also been pressure to use it to stimulate growth in youngsters who have no deficiency but whose parents want them to grow up tall. Summer of 2003, the U.S. FDA approved the use of human growth hormone (HGH) for
  • boys predicted to grow no taller than 5′3″ and
  • for girls, 4′11″
  • even though otherwise perfectly healthy.
  • ACTH — the adrenocorticotropic hormone
  • ACTH of 39 aa peptide.
  • Produced from a larger precursor proopiomelanocortin (POMC).
  • ACTH acts on the cells of the adrental cortex
  • stimulating them to produce
  • glucocortiocoids, like cortisol
  • mineralcortiocoids, like aldosterone
  • Androgens (male sex hormones, like testosterone
  • in the fetus, ACTH stimulates the adrenal cortex to synthesize a precursor of estrogen called dehydroepiandrosterone sulfate (DHEA-S) which helps prepare the mother for giving birth
  • Production of ACTH depends on the intermittent arrival of corticotropin-releasing hormone (CRH) from the hypothalamus.
  • Hypersecretion of ACTH is a frequent cause of Cushing's disease.
  • Alpha Melanocyte-Stimulating Hormone (α-MSH)
  • another cleavage product POMC
  • In fact, α-MSH is identical to the first 13 amino acids at the amino terminal of ACTH.
  • Pituitary cell types of Rathke's pouch
  • Corticotropes, produce (POMC) and cleave it into adrenocorticotropic hormone (ACTH) needed for glucocorticoid synthesis in the adrenal gland
  • Melanotropes, which produce POMC, but cleave it into αMSH (for pigment formation, feeding regulation)
  • Somatotropes, which produce growth hormone
  • Pituitary cell types of Rathke's pouch
  • Lactotropes, which make prolactin (for milk production, uterine contractions)
  • Gonadotropes, which synthesize lutenizing hormone and follicle stimulating hormone (for gonad growth and development)
  • Anterior pituitary cells
  • Somatotropes
  • Lactotropes
  • Thyrotropes
  • Gonadotropes
  • Corticotropes
  • Intermediate pituitary cell, secreting melanocyte-stimulating hormone
  • Magnocellular neurosecretory cells
  • secreting oxytocin
  • secreting vasopressin
  • The Posterior Lobe
  • The posterior lobe of the pituitary releases 2 hormones, both synthesized in the hypothalamus, into the circulation.
  • Antidiuretic Hormone (ADH). ADH is a peptide of 9 amino acids. It is also known as arginine vasopressin. ADH acts on the collecting ducts of the kidney to facilitate the reabsorption of water into the blood. This it acts to reduce the volume of urine formed (giving it its name of antidiuretic hormone).
    • A deficiency of ADH or
    • inheritance of mutant genes for its receptor (called V2)
  • leads to excessive loss of urine, a condition known as diabetes insipidus. The most severely-afflicted patients may urinate as much as 30 liters (almost 8 gallons!) of urine each day. The disease is accompanied by terrible thirst, and patients must continually drink water to avoid dangerous dehydration.
  • Oxytocin peptide of 9 aa
  • Acts on certain smooth muscles:
  • stimulating contractions of the uterus at the time of birth
  • stimulating release of milk when the baby begins to suckle.
  • Oxytocin is often given to prospective mothers to hasten birth.
  • Oxytocin also acts in the brain where it enhances:
  • bonding between males and females after they have mated;
  • bonding between a mother and her newborn;
  • and, in humans, increases the level of one's trust in other people.
  • Hormone Major target organ Major Physiologic effect
  • Anterior
  • GH Liver, adipose tissue
  • Promotes growth (indirectly) and control of protein, lipid and carbohydrate metabolism
  • TSH Thyroid gland Stimulates secretion of thyroid hormones
  • ACTH Adrenal gland (cortex)
  • Stimulates secretion of glucocorticoids
  • PRL Mammary gland
  • Milk production
  • LH Ovary and testis
  • Control of reproductive function
  • FSH Ovary and testis
  • Control of reproductive function
  • Hormone Major target organ Major Physiologic effect
  • Posterior
  • ADH Kidney
  • Conservation of body water
  • OXY Ovary and testis
  • Stimulates milk ejection and uterine contractions
  • REVIEW of Pituitary Gland
  • "master" gland of the endocrine system because it controls the functions of the other endocrine glands.
  • attached to the hypothalumus by nerve fibers.
  • the anterior lobe
  • the intermediate lobe
  • the posterior lobe
  • Each lobe of the pituitary gland produces certain hormones.
  • anterior lobe:
  • GH
  • PRL
  • ACTH
  • TSH
  • FSH
  • LH
  • intermediate lobe:
  • melanocyte-stimulating hormone
  • posterior lobe:
  • ADH and oxytocin
  • Figure 4. Detail from the fresco, "Creation of Adam," by Michelangelo
  • - visible on the ceiling of the Sistine Chapel
  • in the Vatican in Rome, painted 1508-1512.
  • Photograph of the fresco showing God giving spiritual life and
  • intellect to Adam through his touch;(B) The contour of the same image is
  • reminiscent of a midline saggital section of the brain and includes the hypothalamus, pituitary and brainstem.


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